The invention provides a laser marking aid for polyamide plastics, a preparation method for the laser marking aid and application of the laser marking aid. The laser marking aid for the polyamide plastics is characterized by containing the following components in percentage by weight: 55 to 75 percent of hydroxide, 10 to 35 percent of tin oxide, 0.5 to 8 percent of talcpowder, 0.5 to 4 percent of metal antimony, 0.5 to 8 percent of halogen-free flame retardant and 0.5 to 4 percent of lubricant. The preparation method comprises the following steps of: uniformly mixing the tin oxide and the metal antimony by ultrasonic waves or a high-efficiency dispersion machine under the condition that the lubricant is added; and adding the hydroxide, the talcpowder and the halogen-free flame retardant into the mixture, and mixing uniformly. When the laser marking aid is used for plastic manufacture, the adding amount is 0.5 to 20 weight percent. A dark marker with obvious contrast can be formed on the light plastic surface by performing laser printing after the laser marking aid is added into polyamide resin, and adverse phenomena can be avoided; and the laser marking aid can be widely applied in the fields of manufacture of shells of low-voltage electric appliances and the like.